Apparatus for distributing cleaning particles over gas-swept surfaces in heat exchangers and the like



B. o. BROMAN 2,809,018 APPARATUS FOR DISTRIBUTING CLEANING PARTICLES OVER GAS-SWEPT SURFACES IN HEAT EXCHANGERS AND THE LIKE Filed NOV. 13, 1952 @GQQQQQQGQQ @@@@@@@@@9 United States Patent Ofiice 2,809,018 Patented Oct. 8, 1957 APPARATUS FOR DISTRIBUTING CLEANING PARTICLES OVER GAS-SWEPT SURFACES IN HEAT EXCHANGERS AND THE LIKE Bror Broman, Saint Essingen, Sweden, assignor to rsaktigbolaget A. Ekstroms Maskinalfar, Stockholm, we en Application November 13, 1952, Serial No. 320,333

Claims priority, application Sweden November 15, 1951 4 Claims. (Cl. 257--1) The present invention relates to such heating plants and apparatus in which gas-swept heating surfaces are kept clean and free of deposits, soot and the like through the action of cleaning particles, preferably consisting of steel shot or steel pellets which are caused to drop mainly by their own gravity against the heating surfaces which are kept clean and free of deposits, soot and the like through the continuous or intermittent action of such cleaning particles.

In order to ensure that snflicient quantities of cleaning particles shall be directed against the heating surfaces at all the portions thereof where they are needed the cleaning particles are spread out above the heating surfaces by means of suitable distributing devices. Such devices are commonly rotary ones, and they distribute the cleaning particles prior to their dropping against the heating surfaces so that the Wished for surface distribution is attained. The provision of rotary distributors, however, involves mechanical complication, and disturbances in operation may be expected more frequently than with devices which lack moving parts.

It is an object of the present invention to provide distributor means whereby the required surface distribution of the cleaning particles can be attained without the necessity for providing rotary parts within the heat exchanger or other apparatus to be cleaned.

It is a further object of the invention to provide distributing means by which cleaning particles can be spread over surfaces having a considerable length and/ or a great ratio between length and width.

In the drawing Fig. 1 shows a sectional elevation through the upper portion of a heat exchanger provided with a distributing device for cleaning particles according to the invention. :Fig. 2 shows a similar view of a modified arrangement for the distribution of cleaning particles over surfaces of greater length.

In Fig. 1 a heat exchanger the gas swept tubes of which should be kept clean by means of cleaning particles is generally designated with numeral 1, and a flue gas passage from for instance a boiler is designated with 3. Gases from the boiler flow into the heat exchanger through passage 3 and bring with them soot and dust, part of which will eventually settle on the tubes and walls of the heat exchanger 1. These tubes are shown at 4 in the drawing. Through the roof 2 of the heat exchanger a substantially vertical tube 38 extends, and is fitted into the roof 2 in a gas-tight manner. The tube 38 extends to close below the roof 2 and a fixed deflector member 39 is provided below the mouth of the tube which member can be of any suitable shape for instance such as spherical or conical. Above the roof a valve 40 is provided in the tube 38. The valve 40 can be controlled from the outside. Above valve 40 a funnel member 41 for the cleaning particles is provided. The cleaning particles may be transported to the funnel by means of a suitable conveyor or they may be manually fed into the funnel especially in small plants and when the cleaning takes place at intervals. Through tube 38 the cleaning particles drop against the deflector member 39 on opening the valve 40 and are thrown in different directions above the surfaces of tubes 4 to be cleaned.

The apparatus just described can be modified in such a manner that a stream of compressed air or gas containing the cleaning particles is passed through tube 38. The deflector member 39 breaks the paths of the cleaning particles, prevents any direct blasting action against the heating surfaces and makes the cleaning particles scatter in different directions prior to their subsequent dropping over the heating surfaces. The shape of the deflector member may vary considerably provided only that it will give the required surface distribution of the cleaning particles.

1f the horizontal sectional area of the heat exchanger to be cleaned is comparatively extended in one direction the apparatus for distributing the cleaning particles can be modified according to Fig. 2.

In the roof 2 of the heat exchanger a large opening 22 is provided. The opening 22 is covered with a gastight cover 50 which can be insulated against heat. The gases from the boiler flow into the heat exchanger through a passage denoted at 33. In the cover 50 a longitudinally extended slot for the tube 38 is provided. The tube 38 carries below its mouth the deflector member 39, and at its top a funnel 41 as at the device formerly described. The assembly comprising the funnel 41 and the tube 38 with the deflector member 39 is secured to a carriage 42. The carriage 42 is adapted for reciprocatory travel along the slot in the cover 50 by means of a vertically extendedv slot 43 provided in the assembly of funnel and tube in which slot engages a stud member 44 provided at a belt or chain 47 which is suspended on sheaves or wheels 45, 46. Said belt or chain is driven by a motor 48 through transmission means 49, and the assembly of funnel and tube thereby is driven forth and back. The cleaning particles fed to the funnel 41 are distributed above a greater surface corresponding to the path of travel of the carriage. In the tube 38 a valve can of course be provided in the same manner as in the device illustrated in Fig. 1. Further the cleaning particles can be conveyed through tube 38 by means of compressed air or gas. Through the arrangement just described the cleaning particles can be distributed by means of a single distributing device over tubes 51 having surfaces which have a great ratio between length and width.

As will be seen from the above embodiments no rotary members are used within the heat exchanger. Any moving parts are located at the outside where they can more easily be got at, and they are not subjected to the influence of high temperatures and the action of hot gases which will be a considerable advantage and will greatly reduce maintenance costs as well as increase the useful life of the distributor device.

What I claim is:

1. In a heat exchanger, a casing including side walls and a top wall, one of said walls having an opening therein through which flue-gases enter, heat exchange surfaces within the casing of the type comprised at least in part by a plurality of tubes, pipe means extending through one of said walls and having an outlet end disposed above the surfaces, means for feeding solid cleaning particles into said pipe means to flow therethrough, and supported in spaced relation to and adjacent the outlet end of said pipe means a stationary combined particle flow obstructing and deflecting member, said member having a surface adjacent the outlet end of the pipe means adapted to be impacted by the particles and to cause the same to scatter within the cross-sectional area of the casing from a level above the surfaces so that the particles strike and ricochet against the surfaces to clean the same from any deposits and coatings adhering thereto.

2. In a heat interchanging apparatus of the type including a top wall and side walls defining a casing, passage means communicating with the casing and through which flue-gases enter, heat exchange surface within the casing in spaced relation to the top wall and independent of the sidewalls, means including a pipe projecting through the top wall and terminating above the surfaces and through which solid cleaning particles are to be fed into the casing, and a stationary combined obstructing and deflecting member disposed in alignment with and adjacent the terminal end of the pipe, said member having a transverse dimension at least substantially as large as the transverse dimension of the pipe and having a surface facing the pipe adapted to be impacted by the particles as they leave the pipe, and to scatter the particles in different directions within the casing above the surfaces therein to distribute particles throughout the cross-sectional area of the casing so that the particles will impact and richochet against the surfaces to clean the same from any deposits and coatings adhering thereto.

3. In a heat exchanger including a casing having gasswept heating surfaces therein, a top cover for the casing, said top cover having a slot extending longitudinally thereof, a tube extending from above said cover and passing through said slot, said tube terminating above the heating surfaces, a deflection member spaced from but adjacent the terminal end of said tube, means for feeding solid cleaning particles into said tube to flow therethrough and to hit the deflection member to be scattered thereby in different directions throughout the cross-sectional area of the casing so that the particles impact and richochet against the surfaces to clean the same, and means for reciprocating the tube along the slot as the particles are passing through the tube so as to effectively distribute particles throughout substantially the entire cross-sectional area of the casing above the surfaces to facilitate cleaning of the same.

4. In'a heat exchanger as claimed in claim 3, a movable carriage supporting said tube, means for guiding said carriage for reciprocatory movement along the slot and the means for reciprocating the tube along the slot, imparting reciprocatory movement to said carriage.

References Cited in the file of this patent UNITED STATES PATENTS 58,556 Salisbury Oct. 2, 1866 1,045,742 Pontani Nov. 26, 1912 1,058,298 Gregg Aprv 8, 1913 1,916,337 Schmidt July 4, 1933 2,116,879 Day May 10, 1938 FOREIGN PATENTS 212,139 Switzerland Feb. 3, 1941 443,948 Great Britain Mar. 10, 1936 

